Amidines. Part 24. Influences of alkyl substituents at the amidino carbon atom on the sensitivity to substitution at the imino nitrogen atom. pK a Values of N 1 N 1-dimethylamidines
- 1 January 1987
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Perkin Transactions 2
- No. 6,p. 663-668
- https://doi.org/10.1039/p29870000663
Abstract
Three series of N1N1-dimethylamidines, propionamidines, isobutyramidines, and pivalamidines, each containing the same set of 25 substituents Rx at the imino nitrogen atom have been synthesized and their pKa values in 95.6% ethanol (azeotrope) measured. The pKa values were correlated with σ and σ0 constants as well as with the pKa values of the corresponding primary amines RxNH2. Regression parameters for the series studied were compared with those for N1N1-dimethyl-formamidines and -acetamidines. It is shown that the sensitivity of the amidine group to substitution at the imino nitrogen atom depends on the polar effects of substituents at the amidino carbon atom. A good linear correlation between the slope of the correlation line and the σ* value of the substituent at the amidino carbon atom is found.Keywords
This publication has 0 references indexed in Scilit: